Packing gland



Feb. 5, i952 v. E. BOURGEOIS 2,584,252

PACKING GLAND Filed Dec. 21, 1945 AG/TA rop .BLADES n /a 50 uan/CANT,fp/f7- 322 8 A a? 4 "EA- 24 52 8 ZZ fr 9 T* .BEAR/NGS 7 0M7 HEAD o/L13A TH/ :I

r/ I0 IZ I i/ L 13E/412 /A/GS SHAFT FROM Moron Patented Feb. 5, 1952PACKING GLAND Valri E. Bourgeois, laton Bouge, La., assignor to StandardOil Development Company. a corporation of Delaware Application December21, 1945, Serial No. 636,486

This invention relates to improved stuing boxes for revolving shafts,and particularly to stuiiing boxes for shafts exposed to temperature Thestuing' boxes for rotating shafts such as those employed in turbine andagitator constructions are required to be duid-tight under `a widevariation of conditions. It is particularly important in the case ofconstructions in which volatile or corrosive iiuids are present toprevent leakage around the stuiiing boxes. In the prior art, the meansfor preventing such uid leakage z claims; (c1. sos-ssi) has been'to havea liquid seal or a diluting means around the shaft to nullify thedangerous effects of the leaking. In the present invention, the meansfor overcoming the dangerous effects of fluid leakage is the maintenanceof conditions within the material of the stu'ing box best suited forsealing. These conditions are maintained in the device of the present`invention by suitable choice of the packing material. coupled with theuse of a'Y temperature at which the stuiilng box material is mosteiective as a'sealing material.

As a result "of -many recent chemical developments, equipment 'had to bedesigned for operation at low temperatures. The production of syntheticrubber and resinous material has made this requirement particularlynecessary. Thus, synthetic rubber is commonly prepared by a. lowtemperature polymerization of hydrocarbon materials. Temperatures as lowas -200 F; are often employed in such operations. The conditions underwhich the synthetic materials are prepared also require considerableagitation at the low temperatures. YThe problem has thus t* beenpresented of maintaining agitation in low temperature systems. Acritical construction feature in the equipment for such processing isthe stuiiing box which separates the low temperature reaction system,from the means at atmospheric conditions by which control upon thetemperature and the agitating mechanism is maintained. The presentinvention is particularly concerned with the construction of a stuiiinggland which is effective as a seal for rotating shafts exposed to arange of temperature difierentials such as those which occur in thechemical systems operating at low temperatures.

In the past, considerable diiiiculty has been experienced with a packinggland for the preparation of synthetic rubber. The gland which has beenemployed for some time was located near thev reaction system. Under suchconditions, the pacmng became frozen, hardened and sti even during use.When the reactor was warmed up following a few hours' operation toremove polymer adhering to the walls of the reaction vessel. thetemperature of the packing gland was also raised. This increase intemperature caused an excessive leakage of the contents from thereaction vessel. Numerous packing materials and greases wereinvestigated to obtain satisfactory operation under the alternatecooling and heating conditions employed in such reaction systems;however, no packing was found that would give satisfactory performanceat the extremely low operating temperatures. In the present invention.the packing gland previously located near thefreaction system has beenreplaced with a bronzoid bearing. The stufng gland of the presentinvention is located some distance from this bearing and thus somedistance from the zone of low temperature operation. Coupled with thisadvantage of being removed from the low temperature area, additionalfeatures are the circulation of a heating medium in a jacket enclosingthe packing glandin which the packing material is maintained at atemperature at which it is most effective as a sealing material.

The invention will be appreciated by reference to the followingdescription and accompanying drawing. Itis not intended, however, tolimit the invention to the particular embodiment illustrated by thisdescription and drawing since this invention has been successfullyapplied to other rotating shaft devices operating at low temperatures.The drawing presents a sectional 'elevational view of a stufling glandfor an agitator system employed in the preparation of synthetic rubbermaterials from unsaturated hydrocarbons at temperatures of around 150F., the shaft of the agitator being operated from a motor at atmosphericconditions.

Thus, in the drawing, a shaft I0 is shown as making connection by way ofshaftway Illa between a motor, not specifically shown, and the lowerportion of the blades of 'an agitator, partly shown and designated bythe numeral I2, in a reaction Vessel 50 having an encompassing wallportion 50a.

assaasa 3 and the upper and lower annular members 2l and 2lrespectively. I'he annular member 2l' is held in sealing engagement withthe vessel 50 and the bearing-bushing I4 as by means such as the screw30. The packing material is compressedbetween the member 2O and themember 2l.- and thus against the shaft, as by means such as the screw32. The packing material 22 is usually a metallic packing with anasbestos core but may be any packing 'which would be designed foroperating at the temperature maintained at the jacketed packing gland.The jacket 24 permits the circulation therethrough oi' a heating uid forthe heating of the packing material. The iiuid passing through thejacket 24 may be water or a hydrocarbon liquid. The temperaturemaintained with asbestos in the specific embodiment is 80 F. by reasonof the circulation of a hydrocarbon liquid of boiling range above thatof kerosene. The heating uid enters the jacket through line 34 andpasses out through line 3B. The shaft l0 may be lubricated by theinjection of lubricant throughe line 38. Other easily controllable meansof heating the packing material may be employed such as by an electricheating coil. When an electric heating coil is employed, elimination canbe effected of the pump, piping and heat exchanger necessary whencirculating the heating fluid.

In the preparation of butyl rubber from isobutylene and a-diolefin at150 F. in the presence of aluminum chloride in methyl chloride solution,a stuihng box such as previously described and illustrated was foundconsiderably more advantageous than that of the packing gland locatednear the' reaction system as formerly employed. 'The advantages of thepacking gland of this invention are that (1) the packing materialremains soft. pliable and at a uniform temperature during the entirecold and warm servicing cycles, thus minimizing the possibility ofleakages and breakdowns; (2) the reactor operation is not retarded bythe formation of hot spots in the reactor since the heating sys- ReactorEast Middle West Number of Runs l0 17 27 Original Gland, AverageCatalyst,

Hours Per Run 13.6 l0. 0 12.2 Revised Gland, Average Catalyst,

Hours Per Run 21. 4 13. 4 2l. 6

Also, in the packing glands previously used, new packings had to beinstalled following each run and a complete repacking made subsequent toapproximately six runs. With the stumng gland of this invention,fourteen days operation 4 could be carried out without the addition ofpacking. and approximately forty-two days of operation before completerepacking.

What is claimed is:

l. In an apparatus for handling materials at low temperatures, includinga low temperature zone having an encompassing wall, and a shaftextending into the zone through a shaftway in the wall, means forsupporting said shaft substantially to compensate for the lowtemperature effect transmitted therethrough, comprising abearing-bushing in the shaftway extending outwardly therebeyond andsupporting one end of the shaft, a separate, tubular, hollow-walled,stutling box having inner and outer annular end portions, encircling theshaft in radially spaced relation thereto, a soft packing material inthe space between said stuiiing box and the shaft, a gland member in theouter end portion of said stumng box, including means for therebycompressing the packing material against said shaft, conduit meansopening into and from the hollow wall of said stufllng boxforcirculating a heating fluid therethroiigh, means for securing theinner end of said stuffing box to the vessel wall in sealing engagementwith the outwardly extending end of said bearing-bushing, and a bearingfor the other end of said shaft supported in substantially spacedrelation tothe wall of said zone and to saidstufllng box.

2. In an apparatus for handling materials at low temperatures, includinga walled vessel to contain the materials, a shaftway opening through awall of said vessel, a tubular bearingbushing in said shaftway extendingoutwardly therebeyond, and a rotatable shaft extended into the vesselthrough said shaftway and bushing, a seal for said shaft and shaftway,comprising a. separate. tubular, hollow-walled, stuffing box. havinginner and outer annular, end portions, encircling the shaft in radiallyspaced relation thereto, a soft packing material in the space betweensaid stufling box and shaft, a gland member in the outer end portion ofsaid stuing box. including means for thereby compressing the packingmaterial against said shaft, conduit means opening into and from thehollow wall of said stuiling box for circulating a heating fluidtherethrough, and means for securing the inner end oi said stuffing boxto the vessel wall in sealing engagement with the outwardly extendingend of said bearing-bushing.

VALRIE E. BOURGEOIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES `PATENTS Number Name Date 686,737 Josse Nov. 19, 19011,808,353 Jackson June 2. 1931 1,879,774 Temple Sept. 27, 1932 2,131,927Wenzel Oct. 4, 1938 FOREIGN PATENTS Number Country Date 57,'132Switzerland 1911

